This SCCOR application is focused on understanding the complex pulmonary vascular (PV) and right ventricular (RV) remodeling, resulting RV-PV uncoupling, and their crucial impact on morbidity and mortality in Pulmonary Arterial Hypertension (PAH). We will use scleroderma-associated PAH (PAH-SSc) as a clinical paradigm in this application, contrasting it to idiopathic PAH (IPAH), because of its particular severity, lack of response to available PAH therapy, and potential underlying genetic factors that dictate outcome. Because of our extensive PAH-SSc population and our expertise in molecular and diagnostic pulmonary medicine and cardiology, we have the unique opportunity to not only characterize RV-PV responses in PAH-SSc with increased sensitivity and clarity, but to also identify new molecular targets for potential therapy using state of the art imaging, genomic and proteomic technology. Relying on novel imaging systems and molecular tools, we propose to conduct rigorous phenotypic characterization of PAHSSc patients. Focused animal models will provide us with additional candidate genes and proteins for characterization and targeting in human studies. We will then validate the clinical importance of these genes in a large cohort of well-phenotyped patients with PAH, using functional genomics and proteomic approaches with characterization of potentially important polymorphisms. These data will provide new insights into the molecular basis for rational strategies for PAH-SSc patients, and elucidate the relationship of RV-PV dysfunction to the activation of pathological gene expression in genetically susceptible patients. The Hopkins SCCOR application represents a consortium of investigators with multi-disciplinary expertise, and the common goal to utilize state-of-the-art physiological, molecular, and genomic and proteomic approaches as well as novel phenotyping instrumentation that will provide the deepest understanding of the critical pathobiologic processes of RV-PV dysfunction and uncoupling to date, and define key genetic determinants relevant to PAH-SSc. Supported by six highly interactive cores (Administration, Data Management/Bioinformatics, Molecular Pathology, Genomic and Genotyping, Proteomics, and Imaging), the five human and animal projects will utilize novel phenotyping instrumentation and state of the art molecular approaches to PAH-SSc. We anticipate our work will provide a foundation for meaningful translational research that will facilitate development of new strategies, uncover therapeutic targets, and define new biomarkers and prognostic indicators that will limit the current dismal outcome of scleroderma-associated PAH. (End of Abstract) INDIVIDUAL PROJECTS AND CORE UNITS PROJECT 1: Scleroderma-Associated PAH (Hassoun, Paul) DESCRIPTION (provided by applicant): Pulmonary arterial hypertension (PAH) is a devastating syndrome, particularly for patients with systemic sclerosis (SSc), leading almost uniformly to death through right ventricular (RV) failure. We hypothesize that the severity of structural changes involving the pulmonary vasculature (PV) and the RV, resulting in severe RV-PV dysfunction, accounts for diverging responses to therapy and an overall worse outcome in SSc-related PAH (PAH-SSc) as compared to idiopathic PAH (IPAH). Little is known about genetic and phenotypic characteristics that might predict the development of PAH, RV-PV dysfunction, response to therapy, and survival in patients with PAH-SSc. The objectives of this SCCOR project are to (i) develop reliable measures of RV-PV function, (ii) characterize patterns of gene expression and identify candidate gene polymorphisms associated with susceptibility to PAH in SSc, and (iii) use these tools to guide therapy aimed at RV-PV dysfunction in PAH-SSc. In Specific Aim #1, we will characterize optimal measures of RV-PV function by hemodynamic, echo-cardiographic, and Magnetic Resonance Imaging profiles in well-phenotyped patients with PAH-SSc, which will complement specific measurements of RV-PV uncoupling in Project #2. In Specific Aim #2, we will employ high throughput genomic technologies to examine the patterns of gene expression, which explain susceptibility to PAH in subsets of patients with SSc from this project and Project 3. Patterns of expression analyzed within each clinical condition will allow us to determine both concordantly and discordantly regulated gene clusters, link these gene clusters with functional measurements developed in Specific Aim #1, and determine modifier gene profiles associated with PAH-SSc. From these expression studies and those in Projects 4 and 5 we will prioritize novel PAH candidate genes. Specific Aim #3 will test the effects of selected therapies on RV-PV function in PAH-SSc patients and other biomarkers identified in Aims #1 and #2. In Specific Aim #4, we will establish biological validation of prioritized PAH candidate genes via mid- and high-throughput genotyping of DNA procured from a large group (N=1,000) of extensively characterized patients with PAH-SSc (Aim #1), SSc without PAH (Project #3), IPAH, and healthy controls. We will test for association between select variants/haplotypes in candidate genes and susceptibility of PAH in this group and a replicate group of African-Americans. Completion of these studies will provide invaluable information that will guide future mechanistic and clinical studies designed to improve clinical outcomes in PAH-SSc. (End of Abstract)